Recently the solid oxide fuel cell (SOFC) has been a promising means of converting chemical energy into electrical energy by an electro-chemical mechanism. Usually in the conventional SOFC, the Yttria Stabilized Zirconia (YSZ) is used as the electrolyte, the cermet composed of nickel (Ni) and YSZ is used as the anode, and the perovskite composed of LaMnO3 is used as the cathode.
When the SOFC works in a high-temperature environment, the anode fuel, H2, may somehow be suddenly interrupted, such that the air may get into the anode of the fuel cell. Since Ni, the metal catalyst in the fuel, will be oxidized with its volume increased and its expansion coefficient changed, the anode of the SOFC tends to be broken into pieces.
Consequently, there were ways to promote the redox stability of solid oxide fuel cell. La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) has been proposed as one option for the anode material of the SOFC to have improved anode redox stability. However, the catalytic conversion efficiency of LSCM is less than that of Ni and also LSCM is not a good conductor for oxygen (O) ions, therefore, the polarization resistance of LSCM anode is not low enough.
Moreover, to increase the anode redox stability of a solid oxide fuel cell, it is disclosed that another nickel oxide (NiO) or oxidation barrier (Journal of The Electrochemical Society, 153(10), A1929, 2006) layer is coated on the metal substrate. The NiO particle in this layer has a size less than the NiO particles in the anode, and is to be reduced to a porous Ni layer when the full cell is in normal working conditions. The porous Ni layer tends to be re-oxidized more easily, so as to absorb abnormal oxygen leak to improve redox stability of the anode of a solid oxide fuel cell. However, the permeability of fuel gas decreases accordingly.
In the method mentioned above, the thickness of Ni active layer for improving redox stability of solid oxide fuel cell is smaller than the thickness of the support for solid oxide fuel cell. If the microstructure of the support for solid oxide fuel cell can be modified so that fuel gas (for example, hydrogen) can still pass through the support easily, but the oxygen from leakage can be more effectively absorbed in the longer gas channels of the metal support, then the redox stability improvement will be significantly improved.